By producing longer sentences, children also begin to use more complex grammatical structures. Typical early word combinations consist of nouns, verbs, and adjectives. When children first combine words, they tend to omit grammatical words. For example, a child might say, “mommy go store” instead of “mommy goes to the store.” The words “to,” a preposition, and “the,” an article, are missing from the first sentence. Both of these words have a grammatical function. But they are not crucial to understanding the sentence’s meaning. Also missing is the ending –s on the verb go. The child says, “mommy go” instead of “mommy goes.” Parts of words that go on the end of verbs, nouns, or adjectives, are often missing from early word combinations. Another example is excluding the ending -ing that indicates a progressive action. A child might say, “Henry jump” instead of saying, “Henry is jumping.” The ending –s to indicate plural is also missing sometimes. A child might say “more cracker,” instead of “more crackers.” Children usually start excluding words and parts of words when they begin saying three word phrases. But accurate three word phrases are not used consistently until later.

How do children learn to use these grammatical words and parts of words? Studies show that children notice patterns in the speech they hear. They can learn grammatical rules from hearing these patterns. One simple test illustrates this. In the study, an adult shows a child an unknown object with a made up name, such as “fep.” “Fep” is not a word in English. Yet, if you ask an adult native English speaker what the plural of “fep” is, they will tell you that it is “feps.” This is because they know that English words form plurals by adding –s to the end of nouns. Likewise, children who have mastered the English plural rule will be able to tell you that the plural of “fep” is “feps.” They will also know that the plural of the made-up word “blick” is “blicks.” Children have never heard the words “fep” and “blick.” But they have heard other examples of plural words, and can generalize their knowledge to new words.